1. Field of the Invention
The present invention relates to a hand-held power tool having base housing in which there is provided operational means that reciprocates in operation along an operational axis defining a first virtual spatial axis. In direction of a second virtual spatial axis perpendicular to the first spatial axis, the operational axis is spaced from a center of gravity which is formed, for example, by the center of mass of the hand-held power tool, with or without an operational tool fastened thereto. Further, the hand-held power tool has a cover housing which is held at the base housing by flexible decoupling elements which are at least partially spaced from one another with respect to a plane defined by the first and second virtual axis. The cover housing is fixedly connected with the main handle and with side-handle connection means which is formed by fixed connection means in the case of a fixed side handle, and by housing-side connection means in the case of a removable side handle. The housing-side connection means has, for example, a thread or a receiving area for securing a handle-side tensioning belt.
2. Description of the Prior Art
During operation of hand-held power tools of the type mentioned above, due to spacing of the operational axis from the center of gravity, the base housing is subjected to rotational oscillations in opposite directions and which are generated in a rotational direction around the center of gravity in addition to the oscillations along the operational axis. These axial and rotational oscillations can be prevented from being transmitted to the main handle and side handle through the use of a cover housing which is held flexibly on the base housing. The fixed connection of the two handles with the cover housing prevents relative movements between the two handles, and a good handling of the hand-held power tool is ensured in this way. This also yields a relatively large decoupled mass having a positive effect on reducing vibrations between the base housing and the handles.
Vibrations are reduced in all directions by respective suspensions which are largely decoupled from oscillations and which quasi isolate the handle from a large part of the oscillations occurring in operation. Depending on the spring means that is used, there is also provided a damping effect to a degree. This will be referred to concisely hereinafter as decoupling, regardless of the extent of the damping effect.
DE 197 30 356 A1 discloses a hammer drill having a hammer housing at which an outer shell is held so as to enclose it at a distance, this outer shell having a first and second handles. For this purpose, a plurality of flexible articulation points is provided between the hammer drill housing and the outer shell. At these articulation points, a respective shell-side pin engages in a housing-side sleeve with the intermediary of a resiliently flexible material.
This known construction of the decoupling means is intended to achieve a stable guidance and, at the same time, an extensive damping effect in the impact direction.
However, disadvantage of the known hand-held power tool consists in that a sufficient decoupling of the handle from the rotational oscillations of the housing is impossible. Rather, the rotational oscillations are transmitted from the hammer drill housing to the outer shell virtually unimpeded because of the triangular arrangement of the articulation points and the small expansion of the resiliently flexible material acting in the rotating direction at all of the articulation points. Accordingly, a relatively strong vibration still occurs in operation particularly along the second spatial axis.